1. Field of Invention
The present invention relates to light sources. The present invention is more particularly related to light sources used in environments where UV light from the light source is undesirable. The invention is yet more particularly related to a light source in a Liquid Crystal on Silicon (LCoS) projection system such as that used in High Definition (HD) Rear Projection Television (RPTV) applications.
2. Discussion of Background
The projection mechanism within a LCoS microdisplay based video projector is called a light engine. The light engine generally includes a light source and a kernel for modulating light input from the light source. The modulated light is then projected for viewing. The light source may be of a variety of light source types, but is typically a mercury short arc lamp. Note that this type light source outputs a great deal of ultra violet light. Since exposure to UV light can degrade microdisplays, one function of the illuminator is to filter out the UV.
FIG. 1 illustrates a generic illuminator 100. The generic illuminator includes a light source 105 that includes a parabolic reflector. The light source and parabolic reflector output a light beam that is nominally collimated. One characteristic of this light source is that there is a “shadow” in the center of the illumination pattern due to obscuration by the bulb.